1. Field of the Invention
The present invention relates to an image-forming substrate, coated with a layer of microcapsules filled with dye, on which an image is formed by selectively squashing or breaking the microcapsules in the layer of microcapsules.
2. Description of the Related Art
In a conventional type of image-forming substrate coated with a layer of microcapsules filled with liquid dye or ink, a shell of each microcapsule is formed from a suitable photo-setting resin, and an optical image is recorded and formed as a latent image on the layer of microcapsules by exposing it to light rays in accordance with image signals. Then, the microcapsules, which are not exposed to the light rays, are broken, whereby the dye or ink discharges out of the broken microcapsules, and thus the latent image is visually developed by the discharging of the dye or ink.
Of course, each of the conventional image-forming substrates must be packed so as to be protected from being exposed to light, resulting in a wastage of materials. Further, due to the softness of unexposed microcapsules, the image-forming substrates must be handled such that they are not subjected to excess pressure, resulting in an undesired discharging of the dye or ink.
Also, an image-forming substrate, coated with a layer of microcapsules filled with different color dyes or inks, is known. The respective different colors are selectively developed on the image-forming substrate by applying specific temperatures to the layer of color microcapsules. In this case, it is necessary to fix a developed color by irradiation, using a light of a specific wavelength. Accordingly, this color-image-forming system is costly, because an additional irradiation apparatus for the fixing of a developed color is needed, and electric power consumption is increased due to the additional irradiation apparatus. Also, since a heating process for the color development and an irradiation process for the fixing of a developed color must be carried out with respect to each color, this hinders a quick formation of a color image on the color-image-forming substrate.
Therefore, an object of the present invention is to provide an image-forming substrate coated with a layer of microcapsules filled with ink, in which an image can be quickly formed on the image-forming substrate at a low cost, without producing a large amount of waste material.
Another object of the present invention is to provide microcapsules, used in the image-forming substrate, which are filled with ink exhibiting a solid phase at normal ambient temperature.
In accordance with a first aspect of the present invention, there is provided an image-forming substrate which comprises a base member, such as a sheet of paper, and a layer of microcapsules, coated over the sheet of paper, containing at least one type of microcapsule filled with a solid ink. A shell of each microcapsule is constituted so as to be squashed and broken under a predetermined pressure when the solid ink of each microcapsule is thermally melted at a predetermined temperature, whereby discharge of the thermally-molten ink from the squashed and broken microcapsule occurs.
The solid ink may be composed of a pigment and a vehicle that disperses the pigment. The vehicle may comprise a wax material. Preferably, the wax material is carnauba wax, olefin wax, polypropylene wax, microcrystalline wax, paraffin wax, montan wax or the like. The vehicle may comprise a thermoplastic resin material having a low-melting point. Preferably, the low-melting thermoplastic resin material comprises ethylene-vinyl acetate copolymer, polyethylene, polyester, and styrene-methylmethacrylate copolymer or the like. For a cyan pigment, a magenta pigment and a yellow pigment, phthalocyanine blue, rhodamine lake T and benzine yellow G may be utilized, respectively.
The shell of each microcapsule may be formed of a thermosetting resin material. Preferably, the thermosetting resin material comprises melamine resin, urea resin or the like. The shell of each microcapsule may be formed of a thermoplastic resin material exhibiting a high-melting point, which is considerably higher than the aforementioned predetermined temperature. Preferably, the high-melting thermoplastic resin material comprises polyamide, polyimide or the like. Also, the shell of each microcapsule may be formed of inorganic material, such as titanium dioxide, silica or the like. Usually, an outer surface of the shell of each microcapsule is colored by a same single color pigment as a single color exhibited by the sheet of paper.
In accordance with a second aspect of the present invention, there is provided an image-forming substrate, which comprises a base member, such as a sheet of paper, a layer of microcapsules, coated over the sheet of paper, containing a firs t type of microcapsule filled with a first monochromatic solid ink and a second type of microcapsule filled with a second monochromatic solid ink. A shell of the first type of microcapsule is constituted so as to be squashed and broken under a first predetermined pressure when the first monochromatic solid ink of the first type of microcapsule is thermally melted at a first predetermined temperature, whereby discharge of the thermally-molten ink from the squashed and broken microcapsule occurs, and a shell of the second type of microcapsule is constituted so as to be squashed and broken under a second predetermined pressure when the second monochromatic solid ink of the second type of microcapsule is thermally melted at a second predetermined temperature, whereby discharge of the thermally-molten ink from the squashed and broken microcapsule occurs. The first predetermined temperature is lower than the second predetermined temperature, and the first predetermined pressure is higher than the second predetermined pressure, whereby the first and second types of microcapsules are selectively squashed and broken within a localized area of the layer of microcapsules by selectively exerting a first set of the first predetermined temperature and the first predetermined pressure and a second set of the second predetermined temperature and the second predetermined pressure on the localized area of the layer of microcapsules.
The first monochromatic solid ink may be composed of a first pigment and a first vehicle dispersing the first pigment, and the second monochromatic solid ink maybe composed of a second pigment and a second vehicle dispersing the second pigment. When the first vehicle comprises a first wax material, the second vehicle comprises a second wax material exhibiting a melting point higher than that of the first wax material. Also, when the first vehicle comprises a first low-melting thermoplastic resin material, the second vehicle comprises a second low-melting thermoplastic resin material exhibiting a melting point higher than that of the first low-melting thermoplastic resin material.
The shells of the first and second types of microcapsules may be formed of a same material. In this case, a thickness of the shell of the first type of microcapsule is thicker than that of the shell of the second type of microcapsule such that the shell of the first type of microcapsule is durable against the second predetermined pressure, without being squashed and broken, under the second predetermined temperature. Preferably, the shells of the first and second types of microcapsules are formed of a thermosetting resin material, a thermoplastic resin material exhibiting a high-melting point which is considerably higher than the first and second predetermined temperatures, an inorganic material or the like. An outer surface of each shell of the first and second types of microcapsules may be colored by a same single color pigment as a single color exhibited by the sheet of paper.
In accordance with a third aspect of the present invention, there is provided an image-forming substrate, which comprises a base member, such as a sheet of paper, and a layer of microcapsules, coated over the sheet of paper, containing at least one type of microcapsule filled with a solid ink exhibiting a first monochrome, and a plurality of solid ink particles exhibiting a second monochrome. A shell of each microcapsule is constituted so as to be squashed and broken under a predetermined pressure when the solid ink is thermally melted at a first predetermined temperature, whereby discharge of the thermally-molten ink from the squashed and broken microcapsule occurs, and each of the solid ink particles is constituted so as to be thermally broken and melted under a second predetermined temperature higher than the first predetermined temperature, without being subjected to a substantial pressure.
The solid ink may be composed of a first pigment and a first vehicle dispersing the first pigment, and each of the solid ink particles may be composed of a second pigment and a second vehicle dispersing the second pigment and exhibiting a higher melting point than that of the first vehicle. When the first vehicle comprises a wax material, the second vehicle comprises a thermoplastic resin material exhibiting a higher melting point than that of the first wax material. The wax material may comprise either carnauba wax or olefin wax, and the thermoplastic resin material may comprise styrene-methylmethacrylate copolymer. The shell of each microcapsule may be formed of a thermosetting resin material, a thermoplastic resin material exhibiting a high-melting point which is considerably higher than the first predetermined temperature, a suitable inorganic material or the like. An outer surface of the shell of each microcapsule and an outer surface of each solid ink particle may be colored by a same single color pigment as a single color exhibited by the sheet of paper.
In accordance with a fourth aspect of the present invention, there is provided with an image-forming substrate, which comprises a base member, such as a sheet of paper, and a layer of microcapsules, coated over the sheet of paper, containing at least a first type of microcapsule filled with a first type of first-single-color solid ink, and a second type of microcapsule filled with a second type of first-single-color solid ink. A shell of the first type of microcapsule is constituted so as to be squashed and broken under a first predetermined pressure when the first type of first-single-color solid ink is thermally melted at a first predetermined temperature, whereby discharge of the thermally-molten first-single-color solid ink from the squashed and broken microcapsule occurs, and a shell of the second type of microcapsule is constituted so as to be squashed and broken under the first predetermined pressure when the second type of first-single-color solid ink is thermally melted at a second predetermined temperature, whereby discharge of the thermally-molten first-single-color solid ink from the squashed and broken microcapsule occurs. The first predetermined temperature is lower than the second predetermined temperature, whereby the first and second types of microcapsules are selectively squashed and broken within a localized area of the layer of microcapsules by selectively exerting a set of the first predetermined temperature and the first predetermined pressure and a set of the second predetermined temperature and the first predetermined pressure on the localized area of the layer of microcapsules, resulting in a variation in density of the first-single-color solid ink discharged within the localized area of the layer of microcapsules.
The first type of first-single-color solid ink may exhibit either a same density as that of the second type of first-single-color solid ink or a density different from that of the second type of first-single-color solid ink.
In the fourth aspect of the present invention, the layer of microcapsules may further comprise a third type of microcapsule filled with a first type of second-single-color solid ink, and a fourth type of microcapsule filled with a second type of second-single-color solid ink. In this case, a shell of the third type of microcapsule is constituted so as to be squashed and broken under a second predetermined pressure when the first type of second-single-color solid ink is thermally melted at a third predetermined temperature, whereby discharge of the thermally-molten second-single-color solid ink from the squashed and broken microcapsule occurs, and a shell of the fourth type of microcapsule is constituted so as to be squashed and broken under the second predetermined pressure when the second type of second-single-color solid ink is thermally melted at a fourth predetermined temperature, whereby discharge of the thermally-molten second-single-color solid ink from the squashed and broken microcapsule occurs. The third predetermined temperature is lower than the fourth predetermined temperature, whereby the third and fourth types of microcapsules are selectively squashed and broken within a localized area of the layer of microcapsules by selectively exerting a set of the third predetermined temperature and the second predetermined pressure and a set of the fourth predetermined temperature and the second predetermined pressure on the localized area of the layer of microcapsules, resulting in a variation in density of the second-single-color solid ink discharged within the localized area of the layer of microcapsules.
The first type of second-single-color solid ink may exhibit either a same density as that of the second type of second-single-color solid ink of a density different from that of the second type of second-single-color solid ink.
In accordance with a fifth aspect of the present invention, there is provided with an image-forming substrate, which comprises a base member, such as a sheet of paper, and a layer of microcapsules, coated over the sheet of paper, containing at least a first type of microcapsule filled with a first type of first-single-color solid ink, and a second type of microcapsule filled with a second type of first-single-color solid ink. A shell of the first type of microcapsule is constituted so as to be squashed and broken under a first predetermined pressure when the first type of first-single-color solid ink is thermally melted at a first predetermined temperature, whereby discharge of the thermally-molten first-single-color solid ink from the squashed and broken microcapsule occurs, and a shell of the second type of microcapsule is constituted so as to be squashed and broken under a second predetermined pressure when the second type of first-single-color solid ink is thermally melted at a second predetermined temperature, whereby discharge of the thermally-molten first-single-color solid ink from the squashed and broken microcapsule occurs. The first predetermined temperature is lower than the second predetermined temperature, and the first predetermined pressure is higher than the second predetermined pressure, whereby the first and second types of microcapsules are selectively squashed and broken within a localized area of the layer of microcapsules by selectively exerting a set of the first predetermined temperature and the first predetermined pressure and a set of the second predetermined temperature and the second predetermined pressure on the localized area of the layer of microcapsules, resulting in a variation in density of the first-single-color solid ink discharged within the localized area of the layer of microcapsules.
Similar to the fourth aspect of the present invention, the first type of first-single-color solid ink may exhibit either a same density as that of the second type of first-single-color solid ink or a density different from that of the second type of first-single-color solid ink.
In the fifth aspect of the present invention, the layer of microcapsules may further comprise a third type of microcapsule filled with a first type of second-single-color solid ink, and a fourth type of microcapsule filled with a second type of second-single-color solid ink. A shell of the third type of microcapsule is constituted so as to be squashed and broken under a third predetermined pressure when the first type of second-single-color solid ink is thermally melted at a third predetermined temperature, whereby discharge of the thermally-molten second-single-color solid ink from the squashed and broken microcapsule occurs, and a shell of the fourth type of microcapsule is constituted so as to be squashed and broken under a fourth predetermined pressure when the second type of second-single-color solid ink is thermally melted at a fourth predetermined temperature, whereby discharge of the thermally-molten second-single-color solid ink from the squashed and broken microcapsule occurs. The third predetermined temperature is lower than the fourth predetermined temperature, and the third predetermined pressure is higher than the fourth predetermined pressure, whereby the third and fourth types of microcapsules are selectively squashed and broken within a localized area of the layer of microcapsules by selectively exerting a set of the third predetermined temperature and the third predetermined pressure and a set of the fourth predetermined temperature and the fourth predetermined pressure on the localized area of the layer of microcapsules, resulting in a variation in density of the second-single-color solid ink discharged within the localized area of the layer of microcapsules.
Similar to the fourth aspect of the present invention, the first type of second-single-color solid ink may exhibit either a same density as that of the second type of second-single-color solid ink or a density different from that of the second type of second-single-color solid ink.
In accordance with a sixth aspect of the present invention, there is provided with an image-forming substrate, which comprises a base member, such as a sheet of paper, and a layer of microcapsules, coated over the sheet of paper, containing at least a first type of microcapsule filled with a first monochromatic solid ink exhibiting a melting point which falls within a first predetermined range of temperature. A shell of the first type of microcapsule is constituted so as to be squashed and broken under a first predetermined pressure when the first monochromatic solid ink, encapsulated in the shell concerned, is thermally melted under a temperature within the first predetermined range of temperature, whereby discharge of the thermally-molten ink from the squashed and broken microcapsule occurs. The first type of microcapsule is selectively squashed and broken within a localized area of the layer of microcapsules, on which the first predetermined pressure is exerted, by regulating a temperature to be exerted on the localized area of the layer of microcapsules within the first predetermined range of temperature, resulting in a variation in density of the first monochromatic solid ink discharged within the localized area of the layer of microcapsules.
Preferably, the first type of microcapsule is completely squashed and broken within the localized area of the layer of microcapsules when a maximum temperature, within the first predetermined range of temperature, is exerted on the localized area of the layer of microcapsules.
In the sixth aspect of the present invention, the layer of microcapsules may further comprise a second type of microcapsule filled with a second monochromatic solid ink exhibiting a melting point which falls within a second predetermined range of temperature. A shell of the second type of microcapsule is constituted so as to be squashed and broken under a second predetermined pressure when the second monochromatic solid ink, encapsulated in the shell concerned, is thermally melted under a temperature included in the second predetermined range of temperature, whereby discharge of the thermally-molten ink from the squashed and broken microcapsule occurs. The second type of microcapsule is selectively squashed and broken within a localized area of the layer of microcapsules, on which the second predetermined pressure is exerted, by regulating a temperature to be exerted on the localized area of the layer of microcapsules within the second predetermined range of temperature, resulting in a variation in density of the second monochromatic solid ink discharged within the localized area of the layer of microcapsules.
Preferably, the second type of microcapsule is completely squashed and broken within the localized area of the layer of microcapsules when a maximum temperature, within the second predetermined range of temperature, is exerted on the localized area of the layer of microcapsules.
In accordance with a seventh aspect of the present invention, there is provided with a microcapsule which comprises a shell element, and a solid ink, encapsulated in the shell element, exhibiting a predetermined melting point. The shell element is constituted so as to be squashed and broken at a predetermined temperature when the solid ink is thermally melted at the predetermined temperature.
Similar to the first aspect of the present invention, the solid ink may be composed of a pigment and a vehicle that disperses the pigment, the shell of each microcapsule may be formed of a thermosetting resin material, a thermoplastic resin material exhibiting a high-melting point, which is considerably higher than the predetermined temperature and an inorganic material.